Investigation of Transition Metal Catalysts and Substrates for Improved Efficiency and Cost-Effectiveness in Alkaline Water Electrolysis

Abstract

As we move towards the carbon-neutral era, the interest in alkaline water electrolysis (AWE) technology is increasing as it is an eco-friendly and sustainable system. However, there are two main issues with alkaline water electrolysis technology: the high cost of noble metal catalysts and low energy efficiency due to high overpotential in the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER). As a way to solve this problem, research is being actively conducted to apply transition metal catalysts that are relatively inexpensive and have a larger landfill volume than existing high-cost catalysts. Among them, NiFe LDH (Layered Double Hydroxide) has the advantage of having a large surface area with a layered structure and generating highly active hydroxide ions in water electrolysis reactions like NiFeOOH and is attracting attention as a promising catalyst material that can replace precious metals. This study focused on the OER activity of a water electrolysis electrode using a NiFe LDH catalyst on a nickel-based porous catalyzed substrate (CS). Oxygen generation characteristics were evaluated by applying NiFe LDH to a catalyst-type substrate that maximized the active area based on the same Ni material as Ni foam, used as a representative water electrolysis electrode substrate. The NiFe LDH@Ni-CS showed improved OER performance compared to NiFe LDH@Ni foam regarding charge transfer resistance, Tafel slope, and overvoltage. Through this study, it was experimentally confirmed that maximizing the reaction area using a catalytic substrate and applying a highly active NiFe LDH catalyst improved the electrode's extrinsic and intrinsic properties, leading to improved electrode performance.